MB Free Moon Phase is one of the most simple and accurate moon phase calculator software. The program has been uniquely designed to calculate which phase the Moon is passing through on any particular day. The program is based on the astronomy calculations which in turn are dependant upon the relative position of the sun, moon and the earth. Moon phases are caused by the positions of the Earth in relation to that of the Sun and the Moon. On an average it takes 27 days 7 hours and 43 minutes fro the Moon to revolve around the Erath. It is known to all of us that the Moon reflects the light of the Sun. And thus the Sun always illuminates one half of the Moon that is facing the sun, except during lunar eclipses. During its transition around the Earth, when the Sun and the Moon are positioned on the opposite sides of the Earth, the moon to be bright and completely round. This is the 'full moon' day; again, when the moon falls in between the earth and the sun, it is known as the 'Dark Moon' day. Like this the moon phase is ever changing. The software is simple and 'user-friendly'; the best part is, it is totally free of cost and the reading takes just a few minutes to be administered.